Platinum Metals Rev., 1999, 43, (4), 157
High Surface Area Porous Platinum Electrodes
Electrodes with high specific surface areas are needed in batteries, fuel cells and sensors for good efficiency and to aid in the production of small size devices. High surface area electrodes can be produced by controlled electrodeposition, by using the pores in lyotropic liquid crystals, by thermal decomposition of a precursor or by sputtering, the latter being suitable for complex objects.
Now, scientists in the U.S.A. have studied highly porous sputtered platinum dioxide, α-PtO2, films as the precursor to high surface area platinum electrodes (L. Maya, G. M. Brown and T. Thundat, J. Appl. Electrochem ., 1999, 29, (7), 883-888).
PtO2 films 2-4 μm thick, were prepared by reactive sputtering using oxygen-argon, and then reduced to Pt either by room temperature exposure to a hydrogen-argon mixture or by electrochemical reduction. For comparison, Pt films were also produced by sputtering in pure argon.
The reduced films had density of 3.4 g cm-3, while the argon-sputtered films had density 16.3 g cm-3. The microstructure of the precursor films was porous and remained porous on reduction in hydrogen, which suggests a potential use as high specific area electrodes.
Electrochemical reduction of the oxide-derived film showed Pt, oxide and the gold substrate, which indicates it may be possible to used platinum dioxide as a medium for maskless generation of microscopic metallic Pt features using scanning tunneling microscopy. The system could be used to fabricate Pt quantum dots of nanometre diameters for single electron devices.